In office buildings and the like, ventilation is occasionally carried out by drawing fresh outside air into a room, in order to make the indoor space more comfortable. However, when a room that has been air-conditioned by a cooler/heater or the like is ventilated by opening windows, the heat of the air-conditioned air will escape. Then, it will be necessary to again operate the air conditioning device, such as the cooler/heater, for controlling the temperature in the indoor space, resulting in a waste of energy.
For this reason, as a method for performing ventilation of a room while maintaining the above-described air-conditioned state to be as good as possible, heat exchange is performed between a supply air (outside air) supplied into the room and air-conditioned air (return air) discharged from the room. This method also reduces the waste of energy resulting from operating air conditioning devices.
As an apparatus for performing heat exchange ventilation by the above-described method, a heat exchanger unit is known. The heat exchanger unit is operated either in association with an air conditioning device such as an air conditioner or independently, and is installed for ventilating buildings and other various facilities. This heat exchanger unit is installed, for example, in the ceiling of an indoor space SI that is to be ventilated, as shown in FIG. 7. The heat exchanger unit shown here is operated in association with an air conditioning device 82. In a heat exchanger unit 80 as shown in FIG. 7, a heat exchange element 81 carries out heat exchange between return air H1 from the indoor space SI and outside air G1 from an outdoor space SO, using a supply air channel G and an exhaust air channel H, and the return air H1 is released into the outdoor space SO (exhaust steam H2) and the outside air G1 that has been heat-exchanged is sent out into the indoor space SI as supply air G2 (see e.g., Japanese Patent Unexamined Publication JP2000-130720A).
In recent years, increasing attention has been paid to indoor environments, and there is a growing demand for an overall comfortable indoor environment, including factors such as air purity, humidity and content of harmful substances in the air. Therefore, it has been attempted to achieve a more comfortable indoor environment not only by performing ventilation with the above-described heat exchanger unit, but also by providing multiple air conditioning devices, for example, by separately arranging an air conditioning device such as a deodorization unit and a humidification unit, and operating their functions simultaneously.
When providing an additional air conditioning device as described above, however, it is necessary to reserve an additional space to install that air conditioning device. This becomes a more significant problem when air conditioning is performed with various functions by providing a larger number of air conditioning devices.